Recording device



Jan. 5, 1937.

W. EISSFELDT RECORDING DEVICE Filed Aug. 14, 1955 Fig: 2

RE RGDUCING DEVICE ECORDI GDEVIC 15 R N s AMPLI'FYER INVENTOR. ifi-sfeldl werher BY M I ATTORNEY.

Patented Jan; 5, 1937 UNITED STATES PATENT OFFICE- 13 Claims.

The present invention relates to recording and reproducing oi physical variations, more particularly to means for and methods of recording and reproducing sounds, although not limited to such 5 use.

More specificallyfthe invention relates to the art ofreproducing sounds or sonorous vibrations optically and to the preparation of the sound record for that particular method of reproduction.

The term foptical" as used for the purpose of this specification is meant to relate to the use of acoustically modulated light which produces trans-illumination through the sound track or reflection from it, such as is well known from the familiar reproducing systems operating according to the sound-on-film" method now in extensive use in the talking picture art. In the latter, a sound track arranged on the edge of a moving picture film intercepts a beam of light, thus caus- 2 'ing acoustical modulation of the beam passing through the sound track and impinged upon a light sensitive cell which in turn serves to control the intensity of an electric current operating a k sound reproducing device such as a loud speaker.

Systems referred to an non-optical or mechanical" in the present specification include all systems where the recording or reproduction of the sound is accomplished in some way other than by the use of light. First among the mechanical 30 systems is the well known phonograph system in which sound is reproduced from a disc or cylindrical record by means of a stylus being connected either mechanically or electrically to the diaphragm oi the reproducing device such as a loud speaker.

An object of the invention is to provide an improved sound record of the optical reproduction type and an improved method and apparatus for making such records.

40 In the sound-on-film" system above mentioned, the operation is optical not only as far as reproduction is concerned, but also as to recording, because the sound is initially recorded on a light sensitive film by a photographic process. The photographic record produced in accordance with this system usually takes either of two forms. -In one method, known as the -variable area" or "variable width method, the light is passed onto the sensitized photographic film through a slit or 5 opening, the size of which is controlled such as by means of a shutter being vibrated in accordance with the vibrations of the sound waves or sonorous vibrations to be recorded. This produoes a sound track on the developed film which 85 is uniformly opaque, but of variable width or area, in such a manner that the amount of light of a reproducing or pick-up beam of equal cross section to the recording light slit passed through the sound track in the reproducer corresponds to the variation of the sound wave recorded at the corresponding place on the sound track.

In the other method, known as the variable density method, a slit through which the light is caused to pass before it impinges on the film is of constant size, but the intensity of the light source itself is varied in accordance with the variations of the sound or sonorous vibrations to be recorded. This produces on the developed film a sound track of constant width, but of varying degree of transparency, in such a manner that the amount of light of a recording or pick-up beam in the reproducer passed through the sound track is varied in accordance with the variations of the sound as recorded on the corresponding place on the sound track.

One disadvantage of initially recording the soundwaves optically or photographically is the fact that the sound record thus prepared cannot be played back'immediately after it is made, but has first to be developed, thus requiring an elaborate and expensive processing and finishing operation.

Accordingly, it is a further object of the invention to make a sound record of the optical reproduction type thatcan be played back immediately after the sound waves are initially recorded.

Another disadvantage of sound records recorded photographically is the fact that the record carrier such as a photographic film, besides requiring elaborate treatment and development, constitutes a great expense item in a system and method of this type.

It is therefore a further object of the invention to provide a novel. method and system of 40 preparing a sound track mechanically adapted foroptical reproduction and which allows the use of simple and cheap recording material such as paper, regenerated cellulose known by the trade name of Cellophane, or a cellulose derivative and the like.

A more specific object of the invention is to. provide a novel method and means for preparing a sound track of the optical reproduction and "variable width or variable area" type by purely mechanical means.

Another object oi? the invention is the provision of a novel method of and means for preparing a multiple sound track of the optical reproduction and .variable width type purely mechanically with improved characteristics and fidelity of the recorded sound variations.

A further disadvantage incident to sound tracks prepared by the optical or photographic method is due to distortion and to lack of definition of the optical system used, if either of minor quality or when not correctly and accurately adjusted resulting in a blurring or fuzziness or due to halation and other effects such as the grain in the photographic emulsion causing undesirable background noise during the reproduction and a substantial increase in cost oi equipment and negative material as well as operating expenses.

Accordingly, it is a further object of the invention to provide a system and method of preparing a sound track of the optical reproduction tym which is simple and economical both in initial cost and operation and which is substantially free from the disadvantages incident to sound tracks prepared by the optical or photographic method.

cording to the preferred form of the invension, :Eoe sound is recorded by means of a recording pen adapted to supply a writing fluid and vibrated in accordance with the variations of the sound or sonorous vibrations to be recorded. The recording pen consists in a known manner of a pair of metal blades disposed opposite each other and vibrated in accordance with the variations of the sound to be recorded. The record carrier preferably in strip form is moved in a direction normal to the direction of vibration of the recording pen, whereby a variable width sound record is produced directly by purely mechanical means requiring no further treating or other finishing operation. The arrangements may be such that both blades of the recording pen are vibrated or that only one blade is vibrated and the remaining blade arranged in fixed or stationary position. The blades may be vibrated in an opposite sense and the vibrations imparted by a suitable drive mechanism of the type well known in loud speaker and pick-up devices. Several recording pens may be provided suitably connected with each other in order to produce a multiple variable area sound track as will be described in more detail hereafter.

A sound track produced by means of a device of this type has an opaque portion, the width of which varies in accordance with the sound waves. The material on which the sound track is made may be a strip of paper such as transparent paper, sheet metal, or, in general, any material upon which a recordcan be formed either physically or chemically by means of a suitable recording fluid.

In brief, the apparatus according to the invention provides in its preferred form a pen having blades vibrated either directly through mechanical means or indirectly through electrical means in a direction normal to the direction of movement of the record carrier in accordance with the sound waves.

As pointed out, the inventive method and novel recording device is preferably suited for a direct recording or a multiple variable area typ sound track upon any desired carrier material such as paper, with the additional advantage that in the same manner as in optical or photographic recording no "direct contact between the recording element or pen and the record carrier is required. The shape ofthe sound track obtained is' similar to sound tracks obtained by the optical method and has the advantage over sound tracks produced by other mechanical systems such as in accordance with systems of the phonographic type, that it can be reproduced photographically in a simple and cheap manner in any desired number of copies as will be understood.

The various further and also various more speciiic objects, aspects and advantages of the invention will become apparent from the detailed description given below taken in connection with the accompanying drawing which forms a part of this specification.

The invention consists in such novel features, arrangements and combinations 01' parts and methods as are shown, described and claimed in connection with the embodiments herein disclosed by way of example.

Constructional examples of the invention are illustrated in the drawing of which- Fig. l diagrammatically shows an embodiment of a recording apparatus for preparing a multiple variable area's ound record wherein the recording pens are shown on an exaggerated scale in comparison with the remaining parts of the apparatus.

Figs. 2 and 3 illustrate forms of sound tracks obtained by an apparatus according to Fig. 1.

Fig. 4 shows diagrammatically a modified construction of a recording apparatus according to the invention.

Fig. 5 is a side elevational view of the recording pen as shown in Fig. 4.

Fig. 6 illustrates diagrammatically a complete system for recording and reproduction of sounds in accordance with the novel method described by the invention.

Similar reference characters identify similar parts throughout the different views.

As pointed out, the recording device according to the invention comprises a recording element similar to an ordinary writing or drawing pen having blades vibrated in accordance with the variations of the sound or sonorous vibrations to be recorded. The vibrating force is imparted to the blades of the recording pen by a. suitable drive system adapted to transform acoustical vibrations into mechanical vibrations such as the diaphragm of a sound box or similar acoustical device. The operation may be either direct or indirect through an electro-magnetic, electrodynamic or an electro-static or similar arrangement well known in the electrical loud speaker and pick-up art.

The blades of the recording device may either consist of resilient material or held in a. resilient mounting to allow of ready vibratory movement in accordance with the variations of the sounds to be recorded.

Referring to Fig. l of the drawing, I have shown therein three recording pens designated by the numeral {and each comprising a pair of oppositely disposed blades l and I. The ends of the blades are shown to be mounted in a support 3, which may serve as a reservoir for holdin a suitable writing fluid contained between the blades l and I. The blades in the example illustrated are shown to be mounted resiliently such as by means of resilient cushions shown at I in a. manner similar to the known arrangement for mounting the stylus of an electrical pick-up device. The vibration of the blades I and l is e1- fected by means of driving or coupling rods 4 and 4, respectively, connectedto the diaphragm or other vibratory element of an acoustic device such as a microphone or loud speaker operated by the sound waves either directly or through suitable electrical means as is readily understood, and shown more clearly in Fig. 4.

. If both blades l and l' are vibrated such as shown in the example of the Fig. 1, the driving forces should be applied in tandem fashion by means of a double drive system well known from the loud speaker art. If only one of the blades is vibrated and the remaining blade held in fixed position, a single drive system such as shown in Fig. 4 may be provided. The blades may be connected to the driving rods 4 and 4', respec. tively, in any suitable manner known in the construction of loud speakers. be provided with extensions or collars as shown in Figs. 4 and 5 serving for the mounting of the driving rods or connecting links 4 and 4', respectively.

The vibrating blades may be entirely consti tuted by elastic material such as a suitable spring steel or they may be of rigid material, in which case a suitable resilient mounting should be provided to allow of ready vibratory movement as described before.

By means of a recording device of the type described, a sound track of the "variable area type will be obtained such as shown in Figs. 2 and 3 for the purpose of illustration. In the particular example illustrated, the sound track obtained is of the multiple type, that is a plurality in the example shown, three juxtaposed substantially identical sound tracks shown at 8', 8" and 8 are obtained forming a combined multiple track. If a sound track of this type is used in accordance with the optical reproduction method, the amount of light impinged upon the photoelectric cell and passing through a suitable light slit as indicated at s in Figs. 2 and 3 varies in accordance with the ratio of the resultant transparent portions to the opaque portions of the area covered by the light slit s as will be understood.

This in turn corresponds to the variations of the sound recorded on the particular place on the sound record.

The record as shown by Fig. 2 corresponds to the variation of both blades l and I as shown in the example according to Fig. 1, while the record as shown by Fig. 3 corresponds to a variation of one of the blades of the writing pen only with the remaining blade in'flxed or stationary position as will be readily understood. As is understood, the record carrier shown' at 9 movin in a direction at right angle to the direction of vibration of the blades of the recording pen 2 may consist of any suitable material such as paper, cellulose acetate or any other material, as pointed out before.

According to the embodiment of Fig. 4, the inner blades I are shown to be fixed and only the outer blades I vibrated in accordance with the sound variations and connected for this purpose to the recording diaphragm ll of a sound box 10 of a suitable acoustical device such as a microphone and the like through a coupling or driving rod 4 in 3,9 manner similar as described by Fig. 1. In this latter case two identical single sound tracks are obtained which are displaced relatively as compared with the sound tracks shown in Figure 3 and which may beused for individual reproduction such as by splicing the record strip into two halves along its center line. i

A multiple variable area type sound track as shown has the advantage over a single track that the amplitudes of vibration of the blades l and l have to be very small only, thus requiring small driving-forces for the vibrating masses. More- Thus, the blades may over, a multiple track has the advantage of increased fidelity in rendering the higher notes of the sound variations by preventing a cutting off of the highly peaked portions of the sound track curve representing the higher notes or harmonics of the sound or sonorous vibrations. when using a single track "variable area record, great difficulties are experienced in insuring a-reproduction of the higher notes or harmonics of the sound waves by reason of the fact that the width of the light slit is limited and can be kept clear from foreign matter only with great diiilculty. In' a recording arrangement according to the invention on the other hand, the separate sound tracks 8, 8', 8", etc. act in combination in such a manner as'ii'. only a single sound track of corresponding width were used. Thus, distortions caused during the recording process in one track do not affect the other tracks, while when using a single larger track, such distortion would render a reproduction of the higher sound notes impossible.

The record carrier 9, which may consist of a strip of paper as pointed out, is preferably passed over a support l2 provided with rims l3 for preventing lateral displacement of the record carrier and insuring a constant distance between the point of the recording pens 2 and the record carrier. This distance is preferably chosen as small as possible in order to insure a sharp definition of the edge or marginal curve of the sound tracks 8, 8', etc. and inclusion of the higher notes or harmonics of the sound variations in the record.

In Fig. 6 I have shown diagrammatically a complete recording and reproducing outfit using a mechanical method of the type of the invention for sound recording and an'optical system of known construction for the reproduction. The record strip 9 is suitably passed from a supply reel i5, from which it is unwound at the starting end to a take-up reel II on which it is progressively wound at the final end. The reels may be driven by any suitable prime mover such as an electro-motor shown at l8 connected either directly or through a suitable gear or otherdrive mechanism such as a cable or pulley drive mechanism as indicated at I1. The motor i6 is preferably constructed for rotation in both directions to allow winding and unwinding of the record strip-9 in a desired direction. The reversal of the direction may be effected either electrically or by means of a suitable reversing gear or clutch mechanism well known in the art. The recording device with its associated accoustically operated drive system comprising the sound box i0, diaphragm H, and driving rod 4 may be mounted above or in front of the support I! for the record carrier 9.

All the parts are preferably mounted upon a common frame shown at I9. As is understood, the device may be made portable by mounting in a trunk. In the construction according to Fig..

6. the separate parts are mounted upon a rear wall 20 connected to the support or frame l9.

Item [8 represents an electrical amplifier which may be used for amplifying both the recording electrical variations or microphone currents serving to operate the recording diaphragm I I in a recording system and at the same time connect it to the reprodueer.

The latter may be a self-contained separate unit of any type known in the art. In the ar- 5 rangement illustrated the reproducing system shown is combined with the recording apparatus, whereby the winding and drive mechanism as well as the amplifler may be used for both recording and reproducing. The reproducing de- 10 vice, which as is understood may be of any construction known in the art and forms no part of the present invention, has been shown schematically to comprise a drum 2| enclosing a photoelectric cell 22. The drum 2i, in the ex- 16 ample illustrated, consists of two parts separated from each other at a distance equal to the width of the sound track. Item 23 represents an illumination system arranged opposite the sound drum 2i. The latter serves to equalize 21) n a known manner small irregularities in the motion of the record strip such as may be caused, for instance, by the driving mechanism. For this latter purpose I have furthermore shown the record carrier firmly pressed against the rollers 25 25, whereby the record moves in exactconiormity with the rollers and the drum 2!. I have furthermore provided similar rollers 25 arranged before and after the support or guide i2 for the recording apparatus in order to eliminate unde- 30 sirable variations in the sound record.

As will be understood, it is not necessary to provide the sound record with perforations as in the case of sound-on-fllrn systems, since the guide rollers 2d and 25 in connection with the 35 sound drum 2i insure a sufllciently smooth and uniform movement.

The sound rewrd of the type as obtained by a system and method of the invention can be easily reproduced upon sensitized paper by means 40 of any well known photographic copying process as will be understood.

A great advantage of the invention method as pointed out before is the fact that the record w so liable to produce interfering sounds or backgrain noises. A suitable material for this type is cellulose acetate or regenerated cellulose available at low cost on the market and also known under the name of cellophane.

55 According to a further embodiment of the invention, the record carrier may be produced for recording a plurality of sound tracks. one next to the other by moving it alternately in opposite directions by a successive winding and unwind- 90 'ng of the reels l4 and i5 and by a lateral shift of either the record carrier or the recording apparatus as will be understood. In this manner, during the reproduction, after playing one of the sound tracks, the reproduction may be continued 5 immediately by a return movement of the record carrier by the simple operation of a reversing gear and shifting mechanism.

The writing fluid used for preparing sound records according to the invention may con- 7 sist of any easy flowing liquid insuring efllcient surface coverage such as a suitable writing ink, acetone containing coloring matter in solution or uspension and mixed with thinning fluid and I the like. Preferably such materials are used 7 which dry quickly in order to avoid extended drying periods and additional drying arrangements. In place of an ink or writing fluid a suitable chemical compound may be used adapted to :ause a coloring of the record carrier treated in a special manner.

In order to insure a recording of the highest sound notes, care should be taken that the aflinity or adhesion between the writing fluid and the record carrier is higher than the surface tension or cohesion of the fluid. 10

In order to insure a good contact between the record carrier and the support [2, it is furthermore advisable to make the latter of curved shape. Moreover, I may provide pressure rollers in front of and behind the recording pen or pens. These rollers may at the same time serve as drying elements and for this purpose may be suitably heated such as by means of an electric heating resistance or an incandescent lamp structurally connected therewith. Moreover, the support or guide I2 may be heated for this purpose.

According to a further feature of the invention, the recording apparatus may be constructed in a removable or detachable manner similar as in a fountain pen to enable an exchange in case of defects. For this purpose the lower part 3' of the support or container 3 carrying the recording pen or pens 2 may be constructed as an individual element suitably connected to the main part such as by a screwing or similar operation.

As will be understood the supply and take-up reels may be also mounted in a horizontal manner in which case it is only necessary to allow the record strip 9 to form loops in order to insure a smooth movement and to equalize irregularities as may be caused by the driving mechanism.

It is furthermore understood that the reproducing light source 23 of the reproducer may be mounted within the drum 2| and that the photoelectric cell which may be a current generating selenium cell of the barrier plane type cell or any other well known photoelectric cell may be arranged opposite the record carrier 8. Moreover, instead of the drum II, a suitable guide may be provided for the record carrier.

The size of the blades I and I of the recording pen should be as small as possible. In the drawing, the size shown has been greatly exaggerated for the sake of illustration. In order to prevent natural oscillations of the blades, they are preferably provided with suitable stiflening means such as stiflening rods or constructed with'a curved cross section similar to an ordinary writing pen as indicated by'the shading lines in 5;, Fig. 5. I

In order to insure a constant distance of the blades I and I from the record carrier 9, such as about .2 it is preferable to provide small roller guides 16 as shown in Fig. 5 laterally of the 50 blades i and l rolling upon the sound record carrier. It is understood that these rollers should be connected only to those blades maintained in fixed position and not to those vibrated in accordance with the sound variations. If all the blades are vibrated in accordance with the sound variations such as shown in the embodiment according to Fig. 1, the guide rollers should be connected to the stationary parts or support I of the recording device.

While the invention has been described in detail with respect to certain particular preferred examples which give satisfactory results, it will be understood by those skilled in the art, that various changes and modifications may be made .aocaaso without departing from the spirit and scope of the invention as defined in the appendedclaims.

I claim: I

l. A recording apparatus for producing a plurality of identical variable area sound tracks comprising a record carrier moving at uniform speed, a plurality of juxtaposed recording devices, each of said devices having at least one movable element and holding a writing fluid adapted to produce a graphical variable area record upon said carrier, a drivingmeans vibrated in accordance with variations of the sounds to be recorded; and a coupling element connecting said driving means and said movable elements to impart vibratory movement to said movable elements in unison in a direction substantially normal to the direction or movement of said record carrier.

2. A recording apparatus coinprising a record carrier moved in a predetermined direction, a recording device comprised of a pair of oppositely disposed blades adapted to hold a writing fluid and toproduce a graphical record upon said car-.

rier, driving means vibrated in accordance with the variations of the physical magnitude to be recorded, a connecting mechanism between said driving means and at least one of said bladesto' impart vibratory movement thereto in a direction toward and 'away from the other blade and substantially normal to the direction of movement of said carrier to secure a ,variable area record upon said carrier;

3. In a system as claimed in claim 2 in which both of said blades are vibrated by said driving 'means.-

4. In a system as claimed in claim 2 in which one blade of said recording device is vibrated by said driving means and the remaining blade held stationary. K

5. In a system as claimed in claim 2 in which both of said blades are vibrated by said driving means in opposite directions.

- 6. An apparatus for producing'a pluralityroi identical variable area record tracks comprising a record carrier moved in a predetermined direction, a plurality of juxtaposed recording devices, each of said devices being constituted by a pair of oppositely disposed blades adapted to holda writing fluid and to produce a graphical record upon said carrier, driving means vibrated in accordance with the variations of a physical magnitude to be recorded, a coupling element between said driving means and said recording devices to impart vibratory movement to corresponding blades of said recording devices in a direction substantially normal to the direction of movement of said record carrier to simultaneously and equally vary the distance between the blades of each recording device.

, 7. Ina system as claimed in claim 6 in which corresponding blades of said recording elements support including resilient mountings for said blades, said support serving as a reservoir oi writing fluid for said recording elements.

11. A recording apparatus-for producing a plu- '7 said blades are of rigid material, a cup-shaped rality of variable area sound tracks comprising a record carrier, a plurality of recording devices, each or said devices having a pair of oppositely disposed members adapted to hold a writing fluid and to produce a graphical record upon said car.- rier, at'least one member of 'each writing device.

being movable, driving means vibrated in accordance with sound variations to be recorded,

and a common coupling element between said driving means and the movable members of said recording devices.

12. A recording device iorproducing a variable areasoundtrack comprising a pair of oppositely disposed blades adapted to hold a writing fluid,

driving means vibrated in accordance with the variations to be recorded, and a coupling member between said driving means and at least one of said blades for varying the distance'between said blades.

l3. A-recording device for producing a variable area sound track comprising a pair of oppositely and means for vibrating at least one of said blades for varying the distance between the blades in accordance with vibrations of a physical magnitude to be recorded, Y WERNER EISSFEIDI.

disposed blades adapted'to hold a writing fluid, 

